The present invention relates generally to communications, security, and immobilizer systems for vehicles and, in particular, to a circuit board assembly including an integral antenna printed thereon for use in a vehicle immobilizer system.
A vehicle engine is typically started by inserting an ignition key into an ignition lock cylinder of an ignition switch assembly and then turning the ignition key. In order to prevent unauthorized use of a vehicle, electronic immobilizer systems are installed in conjunction with the vehicle's ignition system. The immobilizer system uses an inductive link between a transponder contained in the ignition key and an antenna placed adjacent the ignition lock cylinder. After receiving a signal from the antenna, the transponder contained in the key transmits an immobilizer identification code, which is received by the antenna and transmitted to the vehicle controller. When an identification code transmitted from the transponder of the key matches an identification code preset in the vehicle's controller, the controller allows the engine to be started. The engine, therefore, may only be started by the use of a key incorporating a transponder that transmits a proper identification code.
A continuing goal in immobilizer system design is to efficiently couple energy between the transponder and the antenna and minimize interference with other devices. The optimum means for achieving this is to locate the antenna closer to the key and preferably surrounding the key.
From a manufacturing perspective, it is desirable to locate the antenna on the circuit board that includes the transceiver components that are driving the antenna. Even when installed within the steering column, the circuit board and the antenna have been relatively farther away from the key. This traditionally requires mechanical antenna components, which are disadvantageously costly.
It is desirable to obtain improved antenna performance while lowering the cost of the antenna and improving packaging of the circuit board including the transceiver components that drive the antenna.